The present invention relates to a toothed wheel mechanism and a rotational phase adjuster therewith.
A prior-art rotational phase adjuster for changing a rotational phase difference between a camshaft and a crank shaft in an internal combustion engine is disclosed by each of Publications of Japanese Unexamined Patent Application No. 61-279713, Japanese Unexamined Patent Application No. 62-3111 and Japanese Unexamined Patent Application No. 62-3112.
In the prior-art rotational phase adjuster, a first wheel has an outer-side internal helical gear, a second wheel has an outer-side external helical gear mating with the outer-side internal helical gear and an inner-side internal helical gear, and a third wheel has an inner-side external helical gear mating with the inner-side internal helical gear. The second wheel is moved in an axial direction of the gears relatively to the first wheel and the third wheel to generate a rotationally differential movement between the first wheel and the third wheel. The second wheel is divided into two parts by a plane extending perpendicularly to the axial direction of the gears, and an elastic member between the two parts urges one of the two parts to go away from another one of the two parts in the axial direction of the gears, so that backlashes between the outer-side external helical gear and the outer-side internal helical gear and between the inner-side external helical gear and the inner-side internal helical gear are reduced.